After looking for inexpensive external antennae I came upon a great thread on Whirlpool describing how to make your own. I also wanted a better way to measure the signal strength while I point the dish, and found this page detailing the AT commands for the Optus/Huawei E169.

On a spare Sunday afternoon I put it all together, and to my surprise, it works exceptionally well!

With the dongle plugged into my computer I rarely get a 3G service.  With this woktenna I get 4-5 bars of 3G.  The best I've got is number 13 or -87dBm, a workable connection with 5 bars solid.

Parts:

  • One Mesh fruit bowl from Myers $30
  • One Active USB cable (5m)  from Jaycar $14.95
  • One Paper Towel Holder from a bargain shop $2
  • One beer coaster
  • An old speaker mounting bracket
  • Scraps of aluminium, bike parts and a drink bottle lid.

 

 

 

 

The focal point of the dish is 190^2/(4*105) = 85.95mm.  This is just shy from the edge plane of the rim.

 

 

 

Here's a small ruby script that displays the signal strength directly from the Huawei E169.  It requires

sudo gem install ruby-serialport

 

 

#!/usr/bin/ruby

#puts "hi"

require 'rubygems'

require 'serialport'

require 'readline'

sp = SerialPort.new "/dev/tty.HUAWEIMobile-Modem", 38400

sp.read_timeout == 200


1000.times do

  sp.write "AT+CSQ\r\n"

  j1 = sp.readline

  t = Time.new.to_s

  puts "TIME: " + t + "SIGNAL: " + sp.readline

  sp.flush

  sleep(1)

end

#puts "ho"